Systems for effecting pressure on presser feet for clamps or paper cutting machines



May 5, 1964 c. THUMIM 3,131,926

SYSTEMS FOR EFFECTING PRESSURE ON PREssER FEET FOR CLAMPS 0R PAPERCUTTING MACHINES Filed Oct. 27, 1961 2 Sheets-Sheet l //4 INVENTOR.

C'fl/PL THl/M/M May 5, 1964 Filed Oct. 27, 1961 0/ L PUMP A/A? PUMP c.THUMIM 3,131,926 SYSTEMS FOR EFFECTING PRESSURE ON PRESSER FEET FORCLAMPS OR PAPER CUTTING MACHINES 2 Sheets-Sheet 2 A rrd/P/v K UnitedStates Patent 3,131,926 SYSTEMS FOR EFFECTING PRESSURE 0N PRESSER FEETFOR CLANEPS OR PAPER CUTTING MACHINES Carl Thumim, Lombard, Ill.,assignor to Miehle-Goss- Dexter, Inc, Chicago, Ill., a corporation ofDelaware Filed Oct. 27, 1961, Ser. No. 148,177 8 Claims. (Cl. 269-24)This invention relates to paper cutting machines, and more particularlyto the clamps thereof.

In a previously filed application of Carl Thumim, Serial No. 701,570,filed December 9, 1957, now latent No. 3,025,049, assigned to thepresent assignee, there is disclosed a clamp for a paper cutting machinehaving a plurality of presser feet. The clamp bar is operated byhydraulic pressure while the individual feet are subjected to pneumaticpressure. The purpose of such arrangement is to effect uniform pressureon a paper pile which may vary in vertical contour due to irregularityin thickness of sheets.

The present invention constitutes an improvement of the system disclosedin the prior application, in that it provides for effecting a floatingcondition of the presser feet with respect to the bottom of the clampbar within predetermined Such an arrangement provides for completeflexibility and freedom of self-adjustment of the presser feet to thecontour of the paper pile. However, where the length of the paper pileunder the clamp may vary, the total :air pressure acting on the feetshould likewise vary, to be equal to the total hydraulic pressure on thebar so as to ensure individual operation of the feet on the pile. Thisis of advantage where a paper pile is being out which may be greater inone dimension than in the other, and accordingly relieves the operatorof the necessity for varying air pressure inversely with the length ofthe out as he rotates the pile 90 for cuts in different directions.

The principal object of the system disclosed herein is to overcomeautomatically the need for operator attention to air pressure, byeffecting floating of the presser feet so that under normal operatingconditions, with suitable pressure being supplied, the feet alwaysremain controlledly spaced from the clamp bar when engaging the paperpile in order to exert properly their individual pneumatically effectedpressures on the respective areas of the pile which they contact. Otherobjects and features of the invention will be apparent from thedescription to follow.

Briefly, the invention comprises a construction as generally shown inthe aforementioned application, except that two lengths of so calledTapeswitch are utilized as sensing elements, one such Tapeswitch beingdisposed between the bottom of the clamp bar, rimming the lengththereof, and the oppositely facing surface within each pressure foot.The other Tapeswitch is carried by the clamp bar in such a position thata depressible pin carried on a shoulder of each of the presser feet mayengage it. Thus the arrangement provides for the two T apeswitches beingso positioned that as the feet engage a pile, a normally open solenoidvalve which bleeds from the presser feet pneumatic manifold is closed,thus to fix a maximum spacing between the clamp bar and the presserfeet. On the other hand, the Tapeswitch within the presser feet isactuated when the bar arrives at a predeterminedly close position withrespect to the presser feet, to effect opening of a normally closedvalve for admission of air pressure to the manifold. Thus, theTapeswitches operate in response to an upper or lower positional spacinglimit of any presser feet, starting at the time such prwser foot engagesthe pile on the downward movement of the clamp and ending whensufficient air pressure is in the manifold 3,131,926 Patented May 5.,1964 (and the individual presser feet cylinders) to all feet clear ofthe bottom of the bar.

A detailed description now follows in conjunction with the appendeddrawing in which:

FIGURE 1 a side elevation in section showing the principal parts of thenovel system herein as applied to a clamp bar having individual presserfeet;

FIGURE 2 is a magnified detail of a portion of FIG- URE 1, and,

FIGURE 3 is a fragmentary elevation viewed from the front of the clampbar.

Referring to the drawing, FIGURE 1 illustrates a crosssectional sideelevation of a clamp bar 10 and a U-shaped presser foot '14 associatedtherewith. The presser foot is suspended as by the lost motion boltarrangement 17, in a heretofore known manner, from the pending portion20 of the clamp bar. A rod 23 passes through portion 20 and acts on thesurface 25 of the U-shaped presser foot to transmit pressure from c.piston 28 within a pneumatic chamber 31 fed from a common manifold 34. Aspring 37 biases the piston against the rod. The construction thus fardescribed is substantially the same as disclosed in the aforementionedpatent application, and it will be understood that the clamp bar 10 ishydraulically actuated as by an oil pressure cylinder while the manifold34 is connected by flexible hosing indicated by the phantom line 38 to asource of air pressure 39.

On the base surface 40 of the clamp bar portion 20 there is a TapeswitchT-l which will be understood to run the length of the clamp bar and tobe engageable with the surface 25 of any of the presser feet 14 forpurposes of closing a circuit to be hereinafter described. TheTimeswitch may be secured any suitable manner and comprises a long fiatstrip having a cover of tubular insulation containing conductiveelements such that when pressure is brought to bear anywhere along thestrip, a conmotion is made between local conductive elements at thepoint of pressure. Inasmuch as Tiapeswitch is a well known commercialproduct, no further detailed description is necessary.

A second Tapeswitch T 2 is secured below the horizontal wall portion 42of the clamp bar and is engageable by any one of a series of pins 43carried by respective presser feet, as shown in FIGURE 2, in one of thevertical walls thereof. Thus, each pin 43 is retained in a bore 46 in arespective vertical wall and spring biased as by spring 48 so thatengagement between any pin 43 and Tapeswitch T-Z be resilient in natureand allow for movement of the clamp bar with respect to the presserfeet.

The positioning of the T apeswitches is such as to effect a floatingaction of each presser foot for approximately the spacing indicated bythe letter S of FIGURE 1, indicating the distance between the verticalarrow The surface 40 of clamp bar portion 20 represents the upper limitof free relative movement while surface 25 represents the lower of suchmovement. Of course, the ridge of the Tlape'switch and the bulk of theTapeslwitch will subtract slightly from the degree of such movement in adownward direction of the clamp bar. However, if the Tapeswitch bedisposed in a recess of clamp bar surface 40, then only the ridgethereof subtracts from the free distance.

In order to effect the above free floating function, the systemcomprises a normally closed solenoid operated valve 50 communicatingwith the air supply 39 and also communicating via tubing 38 to manifold34, so that opening of the valve will permit air pressure to reach themanifold which feeds all of the presser feet cyclinders. The system alsocomprises a normally open solenoid operated valve 54 having an air bleedport 57 and connected as indicated by the phantom line 60 to themanifold. Thus, through valve 54 air can bleed from the manifoldoutwardly via port 57, unless the valve is energized to close position.

Finnally, a double-acting relatively fixed switch 64 is nections aremade to the solenoid of valve E4 through QT-Zj shunted by contacts 64a.Thus contacts -ibserve as a conditioning switch for T1 and also ensure.air pressure cutoff when the clamp is at upper position in the event ofmalfunction of T-l.

In operation, assuming the condition shown in FIGURE 1, the circuit isbroken to valve 59, which being normally closed, prevents any airpassing to the manifold 34. Likewise, due to the shunting at contact 64valve 54 is ener- I gized to closed position to prevent air loss bybleeding off of. air. from the manifold. 'Now, if the clamp movesdownwardly switch 64 is released whence air starts to bleed slowly fromthe manifold through valve now de-energiz'ed, and assuming its normallyopen position. Continued downward movement of the clamp ultimatelybrings T-2 into engagement with any of the pins 43 which may'happen tostrike a rising contour of the paper 'file. 'Thereupon closure of T-2energizes valve 54 to close that valve and thus prevent further airbleed.' Assuming that the clamp bar continues its downward movement, T-lengages surface 25 to energize valve-5ll to its open position wherebyair pressure flows to'the manifold and is operative inthe respectivecylinders of the presser feet to force the presser feet downwardly,relative the clamp bar, in order to restore the spacing S. The effect ofthe overall system is to control the air pressure responsive to anypresser foot engaging Tapeswitch T1 or T2, so as .to ensure all presserfeet having vertical freedom of motion with respect to the clamp barwithin the limits imposed by the distance S.

Having thus described my invention, I am aware that many changes may bemade without departing from the spirit thereof, and, therefore, I do notseek to be limited to the precise illustration herein given, except asset forth in the appended claimsi it I claim:

' r 1. In a paper cutting machine, a clamp bar and a plural-. ity ofindividually movable presser feet carried thereby, and means forapplying fluid pressure to individual. feet from a common manifold toeffect uniform pressure on -a paper pile of varying contour, andposition control means for maintaining respectivepresser feet betweentwo limit- 7 ing positionswith respect to said clamp bar so as to ensurefreedom of vertical movement with respect thereto between said twopositions. p I

2. In a device as set forth in claim 1, said position control' meanscomprising sensing elements disposed intermediate said clamp bar andsaid presser feet. adapted to be engaged in respective upper and lowerpositions of said clamp bar with any of said feet, and fluid controlmeans connected'to said manifoid and actuated in response to engagementof one of said sensing elements and operative to respectively admit orexhaust pressure from said manifold to maintain said feet between saidlimiting positions.

3. Inga device as set forth in claim 2, said sensing elements comprisingtwo series of electrical switches and means whereby a switch of oneseries is actuated by av respective presser foot when said clamp bar andpresser foot are in a predetermined maximum spacing condition when saidfoot is applying pressure to a pile, a switch of the other series beingactuated when a respective presser foot approaches a predeterminedminimum spacing when applying pressure to a pile.

4. In a device as set forth in claim 2, said fluid control meanscomprising a normally open bleed valve responsive to a disengagedcondition of one of said sensing elements, to exhaust fluid from saidmanifold and operative to be closed when said sensing element is inengaged condition to determine the maximum spacing ofsaid clamp bar andsaid presser feet;v saidfluid control means also comprising a normallyclosed valve operative to open in response to engagement of the other ofsaid sensing:

elements.

S. In. a device asset forth in claim 2, said sensing elements comprisingfirst and second pluralities of electrical switches and means whereby aswitch of first plurality is actuated by a respective presser foot WhBIISZld. clamp bar and presser foot are in a predetermined maximum spacingcondition when saidfoot is applying'pressure to a pile, a switch of thesecond plurality being actuated" when a respective presser footapproaches a predetermined minimum spacing when applying pressure tosaid pile,

said fiuid'control means comprising a normally'open.

solenoid operated bleed valve responsive to disengaged condition of allof said first plurality of electrical switches to exhaust fluid fromsaid manifold and operative to be closed when said any of said switchesis in an engaged condition; said fluid control means further comprisinga normally closed solenoid operative valve openable in response toengagement of any of the switches of said second plurality, andcircuitry means connecting said pluralities of switches with said valvesfor effecting energi zation of the solenoids thereof.

6. In a device as set forthin claim 5, said fluid control means furtherincluding a switch in relatively fixed position and adapted to beengaged bysaid clamp bar when said clamp bar is in maximum raisedposition, said normally open valve beingoperative to be energized toclosed position responsive to said engagement.

7'. in a device as set forth in claim 6, said latter switch having meansto prevent deenergization of said normally closed valve when said switchis engaged by said clamp bar.

8. In a paper cutting machine, a clamp bar and a plurality ofindividually movable presser feet carried thereby for maintainingrespective presser feet between two limitin positions with respecttosaid clamp bar so as to ensure freedom of vertical movement withrespect thereto between said two positions, including hydraulic powermeans for actuating said clamp bar, said means for applying fluidpressure to said presser feet comprising a source of air pressure.

References Cited in the file of this patent UNITED STATES PATENTS 73,025,049 Thumin Mar. 13, 196;

an... a.

8. IN A PAPER CUTTING MACHINE, A CLAMP BAR AND A PLURALITY OFINDIVIDUALLY MOVABLE PRESSER FEET CARRIED THEREBY AND MEANS FOR APPLYINGFLUID PRESSURE TO INDIVIDUAL FEET FROM A COMMON MANIFOLD TO EFFECTUNIFORM PRESSURE ON A PAPER PILE OF VARYING CONTOUR, AND POSITIONCONTROL MEANS FOR MAINTAINING RESPECTIVE PRESSER FEET BETWEEN TWOLIMITING POSITIONS WITH RESPECT TO SAID CLAMP BAR SO AS TO ENSUREFREEDOM OF VERTICAL MOVEMENT WITH RESPECT THERETO BETWEEN SAID TWOPOSITIONS, INCLUDING HYDRAULIC POWER MEANS FOR ACTUATING SAID CLAMP BAR,SAID MEANS FOR APPLYING FLUID PRESSURE TO SAID PRESSER FEET COMPRISING ASOURCE OF AIR PRESSURE.